The prior rectangle DRA is usually operated in a TE111 mode, and the mode has a linearly-polarized radiation pattern with a wide beam and a bandwidth of approximately 6-10%, and having advantages of low loss and high radiation efficiency, and could be increased to more than 10% by using low-permittivity material with εr≦10.
The beamwidth of the broadside radiation for a typical sectorial antenna is about 120°, and the half power beamwidth (HPBW) of vertical polarization on H-plane is only about 80°, can not fulfill the requirement of the sectorial antenna.
As known, the quality factor is an important parameter to affect the antenna bandwidth. Besides, various radiation patterns can be obtained by choosing proper resonator shapes and exciting proper resonant modes, and the radiation efficiency is affected by the shape of the ground plane, for example, a W-shaped or a V-shaped ground plane is used to lower the cross-polarization level or to increase the gain of antenna. Bigger ground plane can be used to increase the gain and to decrease the backward radiation of antennas. A ground plane of pyramidal-horn shape has also been used to increase the gain of antenna.
U.S. Pat. No. 6,995,713 published on Feb. 7, 2006, entitled “Dielectric resonator wideband antennas ” discloses a wideband antenna consisting of a dielectric resonator or DRA mounted on a substrate with an earth plane. The resonator is positioned at a distance x from at least one of the edges of the earth plane, x being chosen such that 0≦x≦λdiel/2, with λdiel the wavelength in the dielectric of the resonator. This invention applies to wireless networks.
U.S. Pat. No. 7,196,663 published on Mar. 27, 2007 entitled “Dielectric resonator type antennas” relates to a dielectric resonator antenna comprising a block of dielectric material of which a first face intended to be mounted on an earth plane is covered with a metallic layer. According to the invention, at least one second face perpendicular to the first face is covered with a partial metallic layer having a width less than the width of this second face. The invention applies in particular to DRA antennas for domestic wireless networks.
JP Pub. No. 2005142864 published on Jun. 2nd, 2005 entitled “Dielectric resonator antenna” provides a dielectric resonant antenna whose band is widened. The resonant antenna has a dielectric resonator in a specified shape, a mount substrate where a feeder and ground electrodes are formed and the dielectric resonator is mounted, a loop as a conductor line which is formed on a flank of the dielectric resonator and annularly bent while having one end as a first connection point connected to the feeder and the other end as a second connection point connected to the ground electrodes, and a stub which is formed of a conductor extending from the loop of the dielectric resonator separately from the mount substrate. The first connection point is formed closer to the side of the stub than the second connection point and a patch is formed on the top surface of the dielectric resonator by patterning a metal conductor in a specified shape.
The above patents disclose DRAs having rectangular resonator. Also, there are different ways to increase the bandwidth, for example, stacking different sizes of resonators or shaping resonators to merge their frequency bands, coupling and combining the aperture of the slot antenna with a DRA, or sticking a metallic slice to the DRA to provide extra resonant mode and to change the distribution of electric field. However, the prior techniques will make the process more complex, and increase cost and size of the antenna. Moreover, the metallic slice will lower the radiation efficiency due to ohmic loss at high frequency.